I do regularly use Invisifil - and I just ordered a few spools of Kimono silk so I am hoping maybe I could make it stretch using something different in the bobbin. Sounds like Decobob is worth a shot at 80 wt. and I think I will try Invisifil also - as I really want to minimilaze backtracking on the back as well.

I often use #100 silk for quilting the backgrounds of wholecloth quilts. I use Superior, YLI, and FilTec. I've collected all of the colors of each and use whichever most closely matches. The colors are different in each. Superior has a "thread of the month" club that allows you to collect all of the colors at 6 spools per month with free shipping, so that's what I did. I also use this silk for hand applique so it's good to have all of the colors.

I love Superior's 100 wt Kimono silk, which I use frequently. I usually use a close match of Superior's Bottom Line in the bobbin. When I really want the quilting to show, I also quilt with 40 weight polyester threads, such as Superior's Rainbow or Magnifico, and Isacord's 40 wt. embroidery threads. I will still use Bottom Line in the bobbin usually. If I just don't have the right color silk, I sometimes use Bottom Line in the top to quilt with instead of silk. Seems to work almost as well.

I use YLI 100 silk which I bought years ago. It blends into the fabric well even when a different colour but same value. I use ordinary polyester on the back and a 70 needle. I'm not experienced with fine work but it works for me.

I have a love affair going with Superior's Kimono Silk, but my pocketbook doesn't, and I use it sparingly for special projects when I want a good blender with very little thread presence...great for texture and back-tracking with little thread build up showing. I'd like to order a real thread color card in the future. Maybe the Good Fairy of Quilting will bring me every color.

I also like Wonderfil Invisifil (100 wt) especially for the price point, but I don't see that it comes in as many colors and finding a seller with a wide range of colors is challenging. I had problems ordering online from Redrockthreads the other day, and of course, if was after their office hours. A spool of this is a fraction of silk cost and lasts me a long time.

Superior makes ordering so easy and I have my thread in 3 days with no special mailing.

Decobob is made by the same company as Invisifil and is a very fine (80 wt) bobbin thread that has a bit of grip to help keep the bobbin thread where it's supposed to be. A local longarm dealer loves this product.

I used silk for a twin-size quilt I've just completed. Loved it!
It was Superior thread; they suggested a size 70 needle for the
project, I decided that I liked a size 60 better. Did break one
needle when I jerked the quilt sideways. The thread is so fine it
blended well with the multi-color top and looks great. I used the
same thread in the bobbin. Will definitely do it again!